Bi-lognormal Distribution of Sunspot Group Areas

Билогнормальное распределение площадей групп солнечных пятен
Yu. A. Nagovitsyn, Alexei Pevtsov
2021-01-01

Kislovodsk Mountain Astronomical StationRoyal Greenwich Observatorybi-lognormal distributionprecision randomizationsunspot group areas
Abstract We use daily observations from the Royal Greenwich Observatory and Kislovodsk Mountain Astronomical Station of Pulkovo Observatory to study the distribution properties of sunspot areas. To mitigate the poor statistics in the distribution of small areas, we introduce a “precision randomization” approach based on the assumption that all measured areas have a random component within the measurement uncertainty of 1 millionth of the solar hemisphere (M.S.H.). We confirm the presence of two distinct components in the distribution of sunspots previously reported by several authors, and show that the area distribution is described by the sum of two lognormal distributions responsible for small and large groups (sunspots), respectively. We also demonstrate that the area of the main spots in the groups correlates well with the total area of the group, and, thus, the findings derived for the total group areas are equally applicable to the main spots of groups.
1
Daily Royal Greenwich Observatory and Pulkovo Observatory observations reveal two distinct components in the distribution of sunspot group areas.
2
Precision randomization, modeling measurement uncertainty of 1 millionth of the solar hemisphere, mitigates poor statistics for small sunspot areas.
3
Sunspot group areas are described by the sum of two lognormal distributions corresponding to small and large groups.
4
The area of the main spot correlates well with the total group area, making total-area findings applicable to main spots.

sunspot group areas and main-spot areas

the bimodal distribution of sunspot areas, modeled as the sum of two lognormal components for small and large groups, and the correlation between main-spot and total group areas

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2021-01-01
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Yu. A. Nagovitsyn
Alexei Pevtsov
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